One type of coil component well known in the art has a core including a winding portion and a pair of flanges, and a winding wound over the winding portion. Japanese Patent Application Publication No. H07-302719 discloses a technique for protecting the wound portion of the winding with an insulating resin. More specifically, a resin coating is formed over the wound area of the winding by injecting a liquid resin thereon.
In addition, the coil component is conventionally provided with terminal electrodes electrically connected to each end of the winding. The terminal electrodes are provided on the surface-mounting side of the coil component to be electrically connected to electrodes formed on a circuit board when the coil component is mounted on the circuit board. In order to ensure reliable contact between the terminal electrodes and the electrodes on the circuit board, the coil component must be mounted in a precise orientation onto a precise position of the circuit board.
As technological advances are made to increase the performance and reduce the size of electronic devices employing coil components, such as mobile telephones, there has been increasing demand to reduce the size and increase the mounting density of the coil components themselves. To meet this demand, coil components are now being manufactured with a core size of a few millimeters. However, reducing the core size also reduces the size of the winding in the wound area, making it more difficult to fill this wound area with resin.
Further, the reduced size of the coil component has made it more difficult to visually determine the position and orientation of the coil component being mounted on the circuit board, often leading to mounting errors. Changing the shape of the core or adding a marker or the like to the core has helped confirm the correct orientation of the coil component, but increases the difficulty of the manufacturing process with additional steps to change the core shape and apply a marker.